Each adjustment step allows the processor to calculate a calibration constant which is stored in
Flash. Because each step allows a very wide adjustment range it is possible to stop the
instrument functioning completely; if this is suspected the default values listed above should be
set and a complete recalibration should then be performed.
Remote Calibration
Calibration of the instrument may be performed over the RS-232 or USB interface. To completely
automate the process the multimeter and frequency meter will also need to be remote controlled
and the controller will need to run a calibration program unique to this instrument.
The remote calibration commands allow a simplified version of manual calibration to be
performed by issuing commands from the controller. The controller must send the CALADJ
command repeatedly and read the DMM or frequency meter until the required result for the
selected calibration step is achieved. The CALSTEP command is then issued to accept the new
value and move to the next step.
While in remote calibration mode very little error checking is performed and it is the controller’s
responsibility to ensure that everything progresses in an orderly way. Only the following
commands should be used during calibration.
WARNING: Using any other commands while in calibration mode may give unpredictable results
and could cause the instrument to lock up, requiring the power to be cycled to regain control.
CALIBRATION <cpd> [
,
nrf] The calibration control command. <cpd> can be one of three
sub
−
commands:
−
START
Enter calibration mode; this command must be issued before any
other calibration commands will be recognised.
SAVE
Finish calibration, save the new values and exit calibration mode.
ABORT
Finish calibration, do not save the new values and exit calibration
mode.
<nrf> represents the calibration password. The password is only
required with CALIBRATION START and then only if a non
−
zero
password has been set from the instrument’s keyboard. The
password will be ignored, and will give no errors, at all other times.
It is not possible to set or change the password using remote
commands.
CALADJ <nrf>
Adjust the selected calibration value by <nrf>. The value must be in
the range
−
100 to +100. Once an adjustment has been completed
and the new value is as required the CALSTEP command must be
issued for the new value to be accepted.
CALSTEP
Step to the next calibration point.
For general information on remote operation and remote command formats, refer to the following
sections.
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